Which of the following statement is correct?

$\begin{array}{1 1}(a)\;\text{Ethers are insoluble in concentrated acids}\\(b)\;\text{Ethers are soluble in concentrated acids}\\(c)\;\text{Ethers have higher boiling point in comparision to the alcohol of comparable molecular mass}\\(d)\;\text{Ether linkage is more reactive under a wide variety of conditions}\end{array}$